The present invention relates generally to luminaires and more particularly to a system and method for disposing LED and other light sources onto a luminaire such that the luminaire provides uniform lighting and conforms to a structure's metrics.
Lighting fixtures and luminaires are basic lighting devices used in homes, offices and a variety of industrial settings. One criterion when selecting a lighting fixture is that the lighting is visually attractive. Visual attractiveness includes more than the appearance of the luminaire itself but also includes the aesthetic affect of the light provided by the luminaire. Other criteria include low cost, ease of installation, performance, safety and legality. For industrial lighting the cost of installation may be more than the cost of the device because industrial lighting generally requires designs to satisfy many of the above listed criteria. For example, lighting in a warehouse may be required to meet minimum light intensity and safety requirements. This entails the use of a lighting designer or architect who would specify the source and type of luminaire desired for the specified task.
In addition, industrial lighting requires more detailed installation because industrial lighting is often installed as part of a larger design of a factory or workspace. The details of the lighting system must be specified in advance so that pricing, delivery and planning can be properly performed. Also industrial lighting often must meet higher local safety requirements. It is clear that ease of use and lower cost may be effectuated at the design, installation and usage stages of a lighting system.
Improvements that provide for an easier to design or an easier to install lighting system lower overall lighting costs. In addition, improvements that provide ease of manufacture may provide lower costs because fewer parts may be required and the manufacturer can gain from economies of scale. One area that has improved lighting designs is in the construction and use of light emitting diodes (LEDs) as light sources. With the development of high efficiency and high power LEDs it has become possible to incorporate LEDs in industrial lighting. LEDs are low-voltage lamps, requiring a constant direct current (DC) voltage or current to operate optimally. An individual LED may need 2-4V of DC power and several hundred milliamps (mA) of current. When LEDs are connected in series in an array, higher voltage is required. An LED driver acts as this power supply by converting incoming power to the proper low-voltage DC power required by the LEDs.
During operation, the LEDs must be protected from line-voltage fluctuations because changes in voltage can produce a disproportional change in current, which in turn changes light output. (LED light output is proportional to current and is rated for a current range. If current exceeds the manufacturer recommendations, the LEDs can become brighter but their light output can degrade at a faster rate due to heat, shortening useful life. Useful life may be defined as the point where light output declines by 30 percent.) The LED driver regulates the current flowing through the LED during operation and protects it from voltage fluctuations. Led drivers are manufactured and sold as modules including one or more LEDs and control circuitry.
Design of luminaires may require certain physical characteristics because of the location of the luminaire. For example domestic construction often uses wall supports (“studs”) on 16 inch spacing whereas industrial settings may use alternative spacing such as 24 inches. This requires a luminaire system design that comports to the building metrics without excessive costs. Moreover the intensity of lighting provided by the luminaire must provide for uniformity to reduce adverse affects on users.
Accordingly, improvements to LED-based lighting designs that lower costs of manufacture, design or installation are beneficial.